Born on hip-hop and driven delirious by dancehall's sub-bass and garage's ADD beats, U.K. grime is new enough to have more energy than it does discipline which makes it both exhilarating and barely listenable. Vertically Challenged, the first stateside offering from 18-year-old London MC Lady Sovereign, suffers from a similar crisis of maturity. For those not accustomed to grime, the first step is a doozy. Dry synth stabs and slabs of quirky electro embellishments clang above swells of seemingly bottomless bass lines. And while its immediacy and novelty are jarring, the flimsy rhythms at the heart of the tracks make repeated listening unwarranted. Sovereign's easily excitable flow doesn't help matters out either. She effortlessly soars from stoned sneer to fluttering sing-song, but often, she seems oblivious to the beat (not that we could blame her). Of course, that isn't to say that Vertically Challenged isn't good for a few laughs. On "Get Random," she quotes J-Kwon's "Tipsy" along with Luda's "Move Bitch" and concludes that "J. Lo's got a backy/But you can't see mine cuz my trousers are baggy." Yeah, it's silly-stupid, but it's also kinda fun.